“Caliginous” is a literary word used to evoke misty, dark obscurity in a poetic manner. Its Latin root, “cālīginōsus,” is based on the word “cālīgō,” which refers to fog, mist, and vapor. In keeping with this origin, “caliginous” describes the state of not being able to see clearly because the air is full of something like fog or smoke impeding a clear view. When “caliginous” is used poetically, it describes darkness so thick and enveloping, it feels almost physical.